Hydrochemical characteristics of groundwater in the plains of Phalgu River in Gaya, Bihar, India

Assessment of groundwater quality is essential to ensure sustainable use of it for drinking, agricultural, and industrial purposes. The chemical quality of groundwater of Gaya region has been studied in detail in this work to delineate the potable groundwater zones. A total of 30 groundwater samples and 2 surface water samples were collected in and around Gaya district of Bihar. The major cations follow the trend: Ca²⁺?>?Mg²⁺?>?Na⁺?>?K⁺. The domination of calcium ions in the groundwater is due to weathering of rocks. The K⁺ ranged between 0.2 and 47.95 ppm, suggesting its abundance the below desired limit; but some samples were found to be above permissible limit. K⁺ weathering of potash silicate and the use of potash fertilizer could be the source. The major anions abundance followed the order HCO ₃ ^? ?>?Cl^??>?SO ₄ ^2? ?>?NO ₃ ^? ?>?PO ₄ ^3? . Dissolution of carbonates and reaction of silicates with carbonic acid accounts for the addition of HCO ₃ ^? to the groundwater and oxidation of sulphite may be the source of SO ₄ ^2? . Principal component analysis was utilized to reflect those chemical data with the greatest correlation and seven major principal components (PCs) representing >80 % of cumulative variance were able to interpret the most information contained in the data. PC1, PC2 and PC3 reflect the hydrogeochemical processes like mineral dissolution, weathering and anthropogenic sources. PC4, PC5, PC6 and PC7 show monotonic, random and independent relationships.     

Identification and evaluation of the hydrogeochemical processes of the lower part of Wadi Siham catchment area, Tihama plain, Yemen

One hundred forty-eight groundwater samples were collected from the lower part of Wadi Siham catchment area for hydrogeochemical investigations to understand the hydrogeochemical processes affecting groundwater chemistry and their relation with groundwater quality. Groundwater in the study area is abstracted from different aquifers. The study area is characterized by arid climate and extremely high relative humidity. The results indicate that groundwater in the study area is fresh to brackish in nature. The abundance of the major ions is as follows: Na⁺¹?>?Ca⁺²?>?Mg⁺²?≥?K⁺¹ and Cl^?1?>?HCO ₃ ^?1 ?>?SO ₄ ^?2 ?>?NO ₃ ^?1 . Various graphical and ionic ration plots, statistical analyses, and saturation indices calculations have been carried out using chemical data to deduce a hydrochemical evaluation of the study area. The prevailing hydrogeochemical processes operating in the study area are dissolution, mixing, evaporation, ion exchange, and weathering of silicate minerals in the eastern part (recharge areas). The reverse ion exchange and seawater intrusion control the groundwater chemistry along the Red Sea coast areas and few parts of the study area. Deterioration in groundwater quality from anthropogenic activities has resulted from saltwater intrusion along the coastal areas due to groundwater overpumping and extensive use of fertilizers and infiltration of sewage water. Salinity and nitrate contamination are the two major problems in the area, which is alarming considering the use of this water for drinking.     

Characterisation and quality assessment of groundwater with a special emphasis on irrigation utility: Thirumanimuttar sub-basin, Tamil Nadu, India

Thirumanimuttar sub-basin is of particular importance in the study of groundwater quality due to the release of effluents from industries, agricultural, sewage and urban runoff, brining considerable change in water quality. An investigation was carried out by collecting a total of 194 groundwater samples for two seasons to decipher hydrogeochemistry and groundwater quality for determining its suitability for agricultural purposes. The water is neutral to alkaline in nature with pH ranging from 6.78 to 9.22 with an average of 7.37. Higher electrical conductivity (EC) was noted in NW and mid-downstream parts of the study area. Higher NO ₃ ^? was observed during post-monsoon (POM) due to the action of leaching and anthropogenic process. The piper plot reveals the dominance of Na⁺?CCl^? and Na⁺?CHCO ₃ ^? , mixed Ca²⁺?CNa⁺?CHCO ₃ ^? , mixed Ca²⁺?CMg²⁺?CHCO ₃ ^? and Ca²⁺?CSO ₄ ^? types of hydrogeochemical facies. Higher total hardness in the groundwater is due to the effect of dyeing and bleaching industries discharging effluents affects the quality of water. Residual Sodium Carbonate value indicates 56% of the samples are not suitable for irrigation purposes in both seasons. Higher sodium percentage is noted during PRM indicating the dominance of ion exchange and weathering. Higher sodium adsorption ratio was observed during POM indicating the effect of leaching and dissolution of salts into the aquifer matrix. USSL plot indicates 15% of samples record high salinity to medium sodicity. The Permeability Index indicates water is moderate to good for irrigation purposes. In general, groundwater in the study area is influenced by both natural and anthropogenic activities.     

Submarine Groundwater Discharge-Derived Nutrient Loads to San Francisco Bay: Implications to Future Ecosystem Changes

Submarine groundwater discharge (SGD) was quantified at select sites in San Francisco Bay (SFB) from radium (²²³Ra and ²²⁴Ra) and radon (²²²Rn) activities measured in groundwater and surface water using simple mass balance box models. Based on these models, discharge rates in South and Central Bays were 0.3?C7.4?m³?day^?1?m^?1. Although SGD fluxes at the two regions (Central and South Bays) of SFB were of the same order of magnitude, the dissolved inorganic nitrogen (DIN) species associated with SGD were different. In the South Bay, ammonium (NH ₄ ⁺ ) concentrations in groundwater were three-fold higher than in open bay waters, and NH ₄ ⁺ was the primary DIN form discharged by SGD. At the Central Bay site, the primary DIN form in groundwater and associated discharge was nitrate (NO ₃ ^? ). The stable isotope signatures (??¹⁵N_NO3 and ??¹⁸O_NO3) of NO ₃ ^? in the South Bay groundwater and surface waters were both consistent with NO ₃ ^? derived from NH ₄ ⁺ that was isotopically enriched in ¹⁵N by NH ₄ ⁺ volatilization. Based on the calculated SGD fluxes and groundwater nutrient concentrations, nutrient fluxes associated with SGD can account for up to 16?% of DIN and 22?% of DIP in South and Central Bays. The form of DIN contributed to surface waters from SGD may impact the ratio of NO ₃ ^? to NH ₄ ⁺ available to phytoplankton with implications to bay productivity, phytoplankton species distribution, and nutrient uptake rates. This assessment of nutrient delivery via groundwater discharge in SFB may provide vital information for future bay ecological wellbeing and sensitivity to future environmental stressors.     

Spatial control of groundwater contamination,using principal component analysis

A study on the geochemistry of groundwater was carried out in a river basin of Andhra Pradesh to probe into the spatial controlling processes of groundwater contamination, using principal component analysis (PCA). The PCA transforms the chemical variables, pH, EC, Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO \(_3^- \) , Cl^?, SO \(_4^{2-} \) , NO \(_3^-\) and F^?, into two orthogonal principal components (PC1 and PC2), accounting for 75% of the total variance of the data matrix. PC1 has high positive loadings of EC, Na⁺, Cl^?, SO \(_4^{2-} \) , Mg²⁺ and Ca²⁺, representing a salinity controlled process of geogenic (mineral dissolution, ion exchange, and evaporation), anthropogenic (agricultural activities and domestic wastewaters), and marine (marine clay) origin. The PC2 loadings are highly positive for HCO \(_3^- \) , F^?, pH and NO \(_3^- \) , attributing to the alkalinity and pollution controlled processes of geogenic and anthropogenic origins. The PC scores reflect the change of groundwater quality of geogenic origin from upstream to downstream area with an increase in concentration of chemical variables, which is due to anthropogenic and marine origins with varying topography, soil type, depth of water levels, and water usage. Thus, the groundwater quality shows a variation of chemical facies from Na⁺ > Ca²⁺ > Mg²⁺ > K⁺: HCO \(_3^- \) > Cl^? > SO \(_4^{2-}>\) NO \(_3^- \) > F^?at high topography to Na⁺ > Mg²⁺ > Ca²⁺ > K⁺: Cl^? > HCO \(_3^- \) > SO \(_4^{2-}>\) NO \(_3^- \) > F^? at low topography. With PCA, an effective tool for the spatial controlling processes of groundwater contamination, a subset of explored wells is indexed for continuous monitoring to optimize the expensive effort.     

Assessment of hydrogeochemical processes in a coastal region: Application of multivariate statistical model

Hydrogeochemical studies have been carried out in a coastal region, using multivariate statistical model, for better understanding the controlling processes that influence the aquifer chemistry. Two principal components (PC1 and PC2) are extracted from the data set of chemical variables (pH, TDS, Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO ₃ ^? , Cl^?, SO ₄ ^2? , NO ₃ ^? and F^?), which account for 79% of the total variation in the quality of groundwater. The PC1 (salinity controlled process) includes the concentrations of TDS, Mg²⁺, Na⁺, K⁺, Cl^?, SO ₄ ^2? and NO ₃ ^? , while the PC2 (alkalinity controlled process) comprises the concentrations of pH, HCO ₃ ^? and F^?. The spatial distribution of PC scores identifies the locations of high salinity and alkalinity processes. The first process corresponds to the influences of geogenic, anthropogenic and marine sources, and the second one to the influence of water-soil-rock interaction. Thus, the present study shows the usefulness of multivariate statistical model as an effective means of interpretation of spatial controlling processes of groundwater chemistry.     

First principles quantum mechanical calculation of the electric dipole polarizabilities of the borate,carbonate, nitrate and related ions

Electric dipole polarizabilities have been calculated from first principles of quantum mechanics for the BO ₃ ^3? , CO ₃ ^2? , NO ₃ ^? series and for NO ₂ ^? and LiNO₃(g). Calculated trends in average polarizability and polarizability anisotropy in the BO ₃ ^3? -NO ₃ ^? series are in agreement with experiment and can be qualitatively interpreted in terms of the varying energies of the a₁′, a₂″ and e′ symmetry unoccupied MO's of the oxyanions. Embedding a CO ₃ ^2? ion in a D_3h symmetry array of divalent cations reduces both the average polarizability and its anisotropy, particularly when diffuse s and p functions are included in the calculation. Calculations on the gas phase LiNO₃ molecule and on the free NO ₃ ^? ion in the distorted geometry found in LiNO₃(g) allow us to separate polarizability contributions internal to the NO ₃ ^? and Li⁺ ions from those which arise from the Li⁺-NO ₃ ^? interaction. The Li⁺-NO ₃ ^? interaction term so obtained is much smaller than the NO ₃ ^? contribution but is in turn larger than the Li⁺ contribution, suggesting that the inclusion of this interaction term is essential for obtaining accurate results for ion pairs. Although static polarizabilities are in reasonable agreement with experiment for NO ₃ ^? the wavelength dispersion of the polarizability is underestimated by about a factor of two, apparently as a result of inadequacies in the quantum mechanical method. Calculated values are also presented for ¹⁴N NMR shieldings in the nitrogen oxyanions but these are in only qualitative agreement with the experimental values. Similarly, calculated values of magnetic susceptibility are in only qualitative agreement with experiment although trends along the BO ₃ ^3? -NO ₃ ^? series are properly reproduced.     

Geochemical characterization of groundwater from shallow aquifer surrounding Fetzara Lake N. E. Algeria

Hydrogeochemical investigations were carried out around Fetzara Lake, Northeast Algeria, to assess the quality of groundwater for its suitability for drinking and irrigation purposes. The groundwater chemistry is mainly controlled by the water?Crock interactions, but also influenced by other processes such as evapotranspiration and ion exchange. Groundwater samples collected, during two periods (1993 and 2007) from wells in the area were analyzed for pH, EC, TDS, Ca²⁺, Mg²⁺, Na⁺, K⁺, CO ₃ ^2? , HCO ₃ ^? , Cl^?, SO ₄ ^2? , and NO ₃ ^? . The chemical relationships in Piper??s diagram and Gibbs??s diagram suggest that groundwaters mainly belong to noncarbonate alkali type and Cl^? group and are controlled by evaporation dominance, respectively, due to the sluggish drainage conditions, greater water?Crock interaction, and anthropogenic activities. A comparison of the groundwater quality in relation to drinking water quality standards proves that most of the water samples are not suitable for drinking. US Salinity Laboratory??s and Wilcox??s diagrams and %Na⁺ used for evaluating the water quality for irrigation suggest that the majority of the groundwater samples are not good for irrigation.     

Major ion chemistry and metal distribution in coal mine pit lake contaminated with industrial effluents: constraints of weathering and anthropogenic inputs

Ion chemistry of mine pit lake water reveals dominance of alkaline earths (Ca²⁺ and Mg²⁺) over total cation strength, while SO₄ ^2? and Cl^? constitute the majority of total anion load. Higher value of Ca²⁺?+?Mg²⁺/Na⁺?+?K⁺ (pre-monsoon 5.986, monsoon 8.866, post-monsoon 7.09) and Ca²⁺?+?Mg²⁺/HCO₃ ^??+?SO ₄ ² (pre-monsoon 7.14, monsoon 9.57, post-monsoon 8.29) is explained by weathering of Ca?CMg silicates and dissolution of Ca²⁺-bearing minerals present in parent rocks and overburden materials. Silicate weathering supposed to be the major geological contributor, in contrast to bicarbonate weathering does a little. Distribution coefficient for dissolved metals and sorbed to surface sediments is in the order of Cd?>?Pb?>?Fe?>?Zn?>?Cu?>?Cr?>?Mn. Speciation study of monitored metals in surface sediments shows that Fe and Mn are dominantly fractionated in exchangeable-acid reducible form, whereas rest of the metals (Cr, Pb, Cd, Zn, and Cu) mostly in residual form. Cd, Pb, and Zn show relatively higher recalcitrant factor that indicates their higher retention in lake sediments. Factor loading of monitored physico-chemical parameters resembles contribution/influences from geological weathering, anthropogenic inputs as well as natural temporal factors. Ionic load/strength of lake water accounted for geochemical process and natural factors, while pollutant load (viz BOD, COD and metals, etc.) is associated with anthropogenic inputs through industrial discharge.     

Localized zones of denitrification in a floodplain aquifer in southern Wisconsin, USA

A floodplain aquifer within an agricultural watershed near Madison, Wisconsin (USA), was studied to determine whether denitrification was occurring below the surface organic layer. Groundwater levels and concentrations of O₂, Cl^?, NO ₃ ^? , SO ₄ ^2? , dissolved organic carbon (DOC), and major cations were monitored over a 1-year period along a 230-m transect between an agricultural field and a stream discharge point. Seventeen groundwater samples were analyzed for δ¹⁵N_NO3 and δ¹⁸O_NO3 composition. Samples in which NO ₃ ^? was too low for stable isotope analysis were analyzed for excess dissolved N₂. Groundwater NO ₃ ^? concentrations declined between the agricultural field and the discharge point. Chloride and δ¹⁵N_NO3/δ¹⁸O_NO3 data indicated that the drop in NO ₃ ^? was caused primarily by dilution of shallow NO ₃ ^? -rich water with deeper, NO ₃ ^? -depleted groundwater. Two localized zones of denitrification were identified in the upland-wetland transition by their δ¹⁵N_NO3 and δ¹⁸O_NO3 signatures, and two in the stream hyporheic zone by the presence of excess dissolved N₂. The combined stratigraphic, hydrologic, and geochemical data in these locations correspond to groundwater mixing zones where NO ₃ ^? is delivered to subsurface layers that support denitrification fueled by dissolved (e.g. DOC or dissolved Fe(II)) and/or solid-phase (e.g. particulate organic carbon, solid-associated Fe(II), or pyrite) electron donors.     

Urban land-use effects on groundwater phosphate distribution in a shallow aquifer, Nanfei River basin, China

Groundwater, surface water, soil and river sediment samples, and information on land use in the Nanfei River basin (NRB) of China have been analyzed to study the geochemistry, distribution, and mobilization of phosphorus. The distribution of phosphate (PO ₄ ^3??/sup> ) and the relationships between PO ₄ ^3??/sup> and several constituents in groundwater were studied. Partial correlation analysis relating PO ₄ ^3??/sup> to types of land use was conducted using the data analyzing tool SPSS 15.0. The processes controlling the transport of PO ₄ ^3??/sup> are discussed. The conclusions from this study are: (1) urban land use has obvious impact on PO ₄ ^3??/sup> in groundwater, the average concentration of PO ₄ ^3??/sup> being 4.37?mg/L, greater than that resulting from farmland and mixed land use, which have average PO ₄ ^3??/sup> concentrations of 0.10 and 0.18?mg/L, respectively; (2) the partial correlation between PO ₄ ^3??/sup> and types of land use is significant with a coefficient of 0.760; (3) the PO ₄ ^3??/sup> concentrations in surface water are generally higher than those in groundwater, and the total phosphorus (TP) concentrations in river sediments are generally higher than those in soil samples; (4) groundwater is a carrier of PO ₄ ^3??/sup> and is likely responsible for the redistribution of PO ₄ ^3??/sup> in different regions of NRB.     

Using chemical analysis and modeling to enhance the understanding of soil solution of some calcareous soils

The chemistry of soil solutions can be altered by human activities, due to the intense agricultural and husbandry, leading to leaching of nutrients and subsequently elevating ground water levels. Multivariate statistical and inverse geochemical modeling techniques were used to determine the main factors controlling soil solution chemistry of calcareous soils. In this research, a total of 21 calcareous soils was characterized and assessed for soil solution using soil column. The major cations in the studied soil solutions were in the decreasing order as Ca²⁺ > Mg²⁺ > Na⁺ > K⁺. The anions were also arranged in decreasing order as HCO $ _{3}^{ - } $  > Cl $ ^{ - } $  > SO $ _{4}^{2 - } $  > NO $ _{3}^{ - } $ . Concentrations of NO $ _{3}^{ - } $ , P, and K⁺ in soil solutions were in the range of 6.8–307.5 mg l^?1 (mean 63.2 mg l^?1), 5.0–10.4 mg l^?1 (mean 5.9 mg l^?1), and 2.8–54.6 mg l^?1 (mean 11.3 mg l^?1), respectively. Results suggest that the concentration of P in the soil solutions could be primarily controlled by the solubility of dicalcium phosphate dihydrate and dicalcium phosphate. Interactions between soil properties and observed solubility of nutrients were described, and put into empirical multivariate formulations. Obtained equations contained electrical conductivity (EC) as a key factor in determining nutrients solubility. Inverse geochemical modeling of soil solution using PHREEQC indicates the dissolution of calcite, anhydrite, halite, CO₂ (g), N₂ (g), and hydroxyapatite, and precipitation of sulfur. Cation exchange between Ca²⁺, Mg²⁺, K⁺ and Na⁺ occurred with Mg²⁺ and K⁺ into the solution, and Ca²⁺ and Na⁺ out of the solution. Determination of soil solution will improve soil management in the area, and preventing groundwater deterioration.     

Impacts of agricultural irrigation recharge on groundwater quality in a basalt aquifer system (Washington, USA): a multi-tracer approach

Irrigation in semi-arid agricultural regions can have profound effects on recharge rates and the quality of shallow groundwater. This study coupled stable isotopes (²??, ¹⁸O), age-tracers (³H, CFCs, ¹⁴C), ⁸⁷Sr/⁸⁶Sr ratios, and elemental chemistry to determine the sources, residence times, and flowpaths of groundwater and agricultural contaminants (e.g. NO ₃ ^?C ) in the Saddle Mountains Basalt Aquifer in central Washington, USA, where over 80% of the population depend on groundwater for domestic use. Results demonstrate the presence of two distinct types of water: contaminated irrigation water and pristine regional groundwater. Contaminated irrigation water has high NO ₃ ^?C concentrations (11?C116? mg/l), ⁸⁷Sr/⁸⁶Sr ratios (0.70659?C0.71078) within range of nitrogen-based fertilizers, detectable tritium (2.8?C13.4 TU), CFC ages 20?C40?years, high ??¹⁸O values (?16.9 to ?13.5??), and ??100 percent modern ¹⁴C. Pristine regional groundwater has low NO ₃ ^?C concentrations (1?C5? mg/l), no detectable tritium (??0.8 TU), low ??¹⁸O values (?18.9 to ?17.3??) and ¹⁴C ages from ??15 to 33?ky BP. Nitrogen and oxygen isotopes of NO ₃ ^?C , combined with high dissolved oxygen values, show that denitrification is not an important process in the organic-poor basalt aquifers resulting in transport of high NO ₃ ^?C irrigation water to depths greater than 40?m in less than 30? years.     

Quantification of groundwater–seawater interaction in a coastal sandy aquifer system: a study from Panama,Sri Lanka

The Panama coastal aquifer system is an important water resource in the southeast coast of Sri Lanka that provides adequate supplies of water for agriculture and domestic uses. One of the biggest threats to these fragile aquifers is the sea water intrusion. In this study, recharging mechanism and geochemical evaluation of groundwater in the coastal sandy aquifer of Panama were evaluated using chemical and stable isotope techniques. Thirty groundwater samples were collected and analyzed for their major ion concentrations and stable isotope ratios of oxygen (¹⁸O/¹⁶O) and hydrogen (D/H). All studied samples showed a ranking of major anions in the order Cl^? > HCO ₃ ^?  > SO ₄ ^2?  > N-NO₃ ^? while cations showed a decreasing order of abundance with Na⁺ > Ca²⁺ > Mg²⁺ > K⁺. Dominant groundwater hydrogeochemical types were Na–Cl and mixed Ca–Mg–Cl. Results of saturation index calculations indicate that the investigated groundwater body was mostly saturated with respect to calcite, dolomite and gypsum. In addition, stable isotope and geochemical data suggest that fresh groundwater in the aquifer is recharged mainly by local precipitation with slight modification from evaporation and saline water intrusions. Isotope data suggest that mixing of salt water with freshwater occurs in aquifers which are located towards the lagoon. Since the communities in the study area depend entirely on groundwater, an understanding of the hydrogeochemical characteristics of the aquifer system is extremely important for the better water resource management in the region.     

The effect of medium chemistry on the solubility and morphology of brushite crystals

An experimental study of the particulars of the solubility and crystallization of brushite Ca(HPO₄) · 2H₂O from aqueous solution in conditions of a variable pH (6.0–3.0) and the contents of impurity ions (K⁺, Na⁺, NH ₄ ⁺ , Mg²⁺, SO ₄ ^2? , CO ₃ ^2? ) has been conducted. It is established that brushite solubility markedly rises with a decrease in pH from 6 to 3 and slightly rises with an increase in Mg²⁺ and SO ₄ ^2? concentrations. The enrichment in K⁺, Na⁺, and NH ₄ ⁺ does not affect brushite solubility. The changeable chemistry of the medium results in variation of the synthetic crystal habit, from rhombic tabular to thickened prismatic crystals.     

Thermodynamics of plagioclase II: Temperature evolution of the spontaneous strain at the I\bar 1 \leftrightarrow P\bar 1 phase transition in anorthite

The temperature dependence of the lattice parameters of pure anorthite with high Al/Si order reveals the predicted tricritical behaviour of the \(I\bar 1 \leftrightarrow P\bar 1\) phase transition at T _c ^* =510 K. The spontaneous strain couples to the order parameter Q° as x _i∝S _xQ ⁱ Q°² with S _xQ ¹ =4.166×10^?3, S _xQ ² =0.771×10^?3, S _xQ ³ =?7.223×10^?3 for the diagonal elements. The temperature dependence of Q° is $$Q^{\text{o}} = \left( {1 - \frac{T}{{510}}} \right)^\beta ,{\text{ }}\beta = \tfrac{{\text{1}}}{{\text{4}}}$$ A strong dependence of T _c ^* , S _xQ ⁱ and β is predicted for Al/Si disordered anorthite.     

Vulnerability of the groundwater in the quaternary aquifer at El Shalal-Kema area, Aswan, Egypt

El Shalal-Kema area is located east of Aswan town and Nile River. The Quaternary sediments (unconsolidated material of sands, gravels, and clays intercalation) represent the main aquifer in the studied area. Its water is under unconfined condition, and the water table is shallow (vary from 7.5 to 16.3 m). The concerned aquifer is recharged mainly from Aswan Dam Lake, from the excess irrigation water and from septic tanks, where the area is not served by sewage system. The direction of the groundwater movement is generally from south to north. The transmissivity values of the Quaternary aquifer (from three pumping tests) are relatively high (vary from 1,996 to 3,029 m²/day). The exploitation of groundwater is carried out where there is continuous withdrawal for industrial and domestic uses with a total average quantity of groundwater of 71,304 m³ per day (25.67 million m³ per year). The hydrochemical characteristics of the Quaternary aquifer is studied based on the chemical analysis of 29 groundwater and four surface water samples collected from different sites. The chemical composition of the groundwater is dominated by calcium Ca²⁺ from the cations and bicarbonate (HCO ₃ ^? ) from the anions, and the order of cation abundance is Ca²⁺ > Na⁺ > Mg²⁺ > K⁺ and HCO ₃ ^? > SO ₄ ^2? > Cl^? among the anions. The groundwater types are normal chloride water, normal sulfate water, and normal carbonate water. The hypothetical salt combination revealed the presence of different salts arranged in terms of their predominant as Ca(HCO₃)₂, Mg(HCO₃)₂, NaCl, Na₂SO₄, MgSO₄, KCL, NaHCO₃, MgCl₂, CaSO₄, and K₂SO₄. The analytical measurements to the NO₂ and NH₃ reveal that their values decrease in summer and increase in winter due to the stoppage of pumping which leads to the increase of the wastewater quantities that reach the groundwater. The chemical and microbiological analyses show that the aquifer in this area is contaminated with fecal and disease-causing bacteria. The main cause of this contamination is the outflow from the septic tanks; therefore, the construction of sewage network is a vital solution. Chlorination is important to disinfect the groundwater at the tanks before its distribution to the houses.     

Characterization and origin of two Fe3+ EPR spectra in kaolinite

The electron paramagnetic resonance (EPR) spectra of Fe³⁺ in a well cristallized kaolinite from Decazeville in France are well resolved. It is shown that in this sample there are mainly two slightly different spectra, well separated at low temperature and characterized at -150° C by the constants B ₂ ⁰ = 0.112 cm^?1, B ₂ ² = 0.0688 cm^?1 for one and B ₂ ⁰ = 0.116 cm^?1, B ₂ ² = 0.0766 cm^?1 for the second. These two spectra arise from Fe³⁺ substituted for Al³⁺ at the two octahedral positions in equal amounts. The temperature dependence of EPR spectra was studied and was explained by a modification of the octahedral sites.     

Zn and Pb solubility and speciation in aqueous chloride fluids at T-P parameters corresponding to granitoid magma degassing and crystallization

The solubility of all possible Zn and Pb species in aqueous chloride fluids was evaluated by means of thermodynamic simulations in systems ZnO(PbO)-aqueous solution of NaCl (KCl, NaCl + HCl) within broad ranges of temperature (600–900°C), pressure (0.7–5 kbar), and chloride concentrations, under parameters corresponding to the crystallization and degassing of granitoid magmas in the Earth’s crust. Our simulation results demonstrate that the addition of Cl to the fluid phase in the form of Na(K)Cl and HCl significantly increases the concentrations of Cl-bearing Zn and Pb complexes and the total concentration of the metals in the solutions in equilibrium with the solid oxides. In Zn-bearing fluids, the Zn(OH) ₂ ⁰ , ZnOH⁺, and Zn(OH) ₃ ^? —hydroxyl complexes and the ZnCl ₂ ⁰ , and ZnCl⁺ chlorocomplexes, which are predominant at low Cl concentrations (C_Cl < 0.05–0.1 m) give way to ZnCl ₄ ^2? with increasing C_Cl, which becomes the predominant Zn species of the fluid at C_Cl > 0.1–0.5 m throughout the whole temperature range in question and pressures higher than 1 kbar. For Pb-bearing fluids, the T-P-X region dominated by the Pb(OH) ₂ ⁰ , and Pb(OH) ₃ ^? hydroxyl complexes is remarkably wider than the analogous region for Zn, particularly at elevated temperatures (≥700°C) in alkaline solutions. An increase in C_Cl is associated with an increase in the concentration and changes in the speciation of Pb chlorocomplexes: PbCl ₂ ⁰ → PbCl ₃ ^? → PbCl ₄ ^2? . The concentrations of Zn and Pb chlorocomplexes increase with increasing pressure, decreasing temperature, and decrease pH with the addition of HCl to the system. It is demonstrated that the solubility of ZnO at any given T-P-X in alkaline solutions with low chloride concentrations are lower than the solubility of PbO. The Zn concentration increases more significantly than with the Pb concentration with increasing C_Cl and decreasing pH, so that the Zn concentration in acidic solutions is higher than the Pb concentration over broad ranges of temperature, pressure, and Cl concentration. Chloride complexes of Zn (ZnCl ₂ ⁰ , and ZnCl ₄ ^2? ) and Pb (PbCl ₂ ⁰ , and PbCl ₃ ^? are proved to be predominant within broad T-P-X-pH ranges corresponding to the parameters under which magmatic fluid are generated. Our simulation results confirm the hypothesis that chlorocomplexes play a leading role in Zn and Pb distribution between aqueous chloride fluids and granitic melts. These simulation results are consistent with experimental data on the Zn and Pb distribution coefficients (D(Zn)^f/m and D(Pb)^f/m, respectively) between aqueous chloride fluids and granitic melts that demonstrated that (1) D(Zn)^f/m and D(Pb)^f/m increase with increasing Na and K chloride concentrations in the aqueous fluid, (2) both D(Zn)^f/m and D(Pb)^f/m drastically increase when HCl is added to the fluid, and (3) (D(Zn)^f/m is higher than D(Pb)^f/m at any given T-P-X parameters. The experimentally established decrease in D(Zn)^f/m and D(Pb)^f/m with increasing pressure (at unchanging temperature and Cl concentration) is likely explained by an increase in the alkalinity of the aqueous chloride fluid in equilibrium with granite melt and, correspondingly, a decrease in the Zn and Pb solubility in this fluid.     

Characterization, classification, and determination of drinkability of some Algerian thermal waters

In this study, the physicochemical parameters (Conductivity, pH, Cl^?, HCO ₃ ^? , PO ₄ ^3? , SO ₄ ^2? , NO ₃ ^? , NO ₂ ^? , F^?, TH, Ca²⁺, K⁺, Mg²⁺, Na⁺, and DS) were determined for 41 samples collected from fourteen places in Algeria. The temperature of the thermal water samples at collection sites varied from 26°C to 86°C. pH values varied from 6.5 to 8.5 (i.e., from slightly acidic to moderately alkaline); 90.24% of the samples exhibited relatively high salinity (DS?=?550–5,500 mg L^?1). Total hardness measurements indicated these waters to be moderately hard. Forty-six percent of the samples are Na–Cl in character. The ratios Na⁺/Ca²⁺, Na⁺/Mg²⁺, and (Na⁺ + K⁺)/(Ca²⁺ + Mg²⁺) were high in 90.24% of the samples. This indicates the ion exchange process is important, which indicates that most of the Algerian thermal waters had developed over a long period at a depth sufficient to react with the rock. Statistical analyses of the physicochemical data gave positive correlation values, thereby enabling good interpretation of the results and revealing the composition of ions present in the thermal waters, as well as some information about their origin. The therapeutic properties associated with thermal waters encourage people at spas to drink the water they bathe in. Therefore, we examined the drinkability of these thermal waters. World Health Organization (WHO 1993) standards were used to evaluate the thermal water quality for drinking. With respect to hardness, the samples were classified as moderately hard (58.54% of the samples), very hard (36.58% of the samples), and soft (4.88% of the samples). The drinkability study shows that only 16 samples of the investigated waters were drinkable and thus could be consumed without special precaution.